Plasma processing method and apparatus

ABSTRACT

Plasma is generated in the interior of a vacuum chamber to process a high melting metal film formed on a substrate, while supplying gas into the vacuum chamber and simultaneously exhausting the interior of the vacuum chamber to control to a specified pressure, by supplying a high-frequency power of a 30 MHz to 3 GHz frequency to an antenna provided within the vacuum chamber in opposition to the substrate placed on a substrate electrode within the vacuum chamber, by supplying a high-frequency power of a 100 kHz to 20 MHz frequency different from the above frequency to the antenna.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a plasma processing method andapparatus to be used for manufacture of semiconductor or other electrondevices and micromachines.

[0002] In the manufacture of semiconductor or other electron devices andmicromachines, thin-film processing techniques using plasma processinghave been becoming increasingly important in recent years.

[0003] As an example of conventional plasma processing methods, plasmaprocessing using a patch-antenna type plasma source is described belowwith reference to FIG. 3. Referring to FIG. 3, while interior of avacuum vessel 51 is maintained to a specified pressure by introducing aspecified gas from a gas supply unit 52 into the vacuum vessel 51 andsimultaneously performing exhaustion by a turbo-molecular pump 53 as anexhausting unit, a high-frequency power of 100 MHz is supplied by anantenna use high-frequency power supply 54 to an antenna 55 provided soas to project into the vacuum vessel 51. Then, plasma is generated inthe vacuum vessel 51, allowing plasma processing to be carried out witha substrate 57 placed on a substrate electrode 56.

[0004] There is also provided a substrate-electrode use high-frequencypower supply 58 for supplying high-frequency power to the substrateelectrode 56, making it possible to control ion energy that reaches thesubstrate 57. The high-frequency power supplied to the antenna 45 is fedto a proximity of the center of the antenna 55 via an antenna-usematching circuit 59 by a feed bar 60. A dielectric plate 61 issandwiched between the antenna 55 and the vacuum vessel 51, and the feedbar 60 serves to connect the antenna 55 and the antenna-usehigh-frequency power supply 54 to each other via a through hole providedin the dielectric plate 61. Also, the surface of the antenna 55 iscovered with an antenna cover 65.

[0005] Further, a slit 64 is provided so as to comprise a groove-shapedspace between the dielectric plate 61 and a dielectric ring 62 providedat a peripheral portion of the dielectric plate 61, and a groove-shapedspace between the antenna 55 and a conductor ring 63 provided at aperipheral portion of the antenna 55.

[0006] The turbo-molecular pump 53 and an exhaust port 73 are disposedjust under the substrate electrode 56, and a pressure-regulating valve74 for controlling the vacuum vessel 51 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 56 andjust over the turbo-molecular pump 53. The substrate electrode 56 isfixed to the vacuum vessel 51 with four pillars 75.

[0007] In the plasma processing described in the prior-art example,however, etching a high melting metal film formed on the substrate 57would involve deposition of an electrically conductive deposited film onthe antenna cover 65, in which case poor close-contactability of theconductive deposited film or occurrence of abnormal discharge at thesurface of the antenna cover 65 would make it more likely to occur thatthe conductive deposited film would be peeled off, falling onto thesubstrate 57 as dust in some cases. According to a result of the presentinventors' experiments, when the substrate 57 coated with a 200 nm thickiridium film was etched to a quantity of 7 pieces, 1000 or more dustparticles having 0.23 μm or larger particle diameters were generated onthe substrate 57.

[0008] Further, in the plasma processing described in the prior-artexample, there is another issue that the temperature of the antennacover 65 increases due to plasma exposure. Since the antenna cover 65and the antenna 55 are vacuum-insulated from each other, the temperatureof the antenna cover 65 gradually increases over repeated plasmaprocessing. According to a result of the present inventors' experiments,it was found that the temperature of the antenna cover 65 increases upto 170° C. after 5-min. plasma processing and 1-min. vacuum holding isrepeated six times. Such an abrupt change in the temperature of theantenna cover 65 may cause not only occurrence of dust but also cracksof the antenna cover 65.

[0009] In view of these and other prior-art issues, an object of thepresent invention is to provide a plasma processing method and apparatuswhich is less liable to occurrence of dust and cracks of the antennacover.

SUMMARY OF THE INVENTION

[0010] In order to achieve the above object, the present invention hasthe following constitution.

[0011] According to a first aspect of the present invention, there isprovided a plasma processing method for generating plasma in a vacuumvessel, by supplying a high-frequency power of a 30 MHz to 3 GHzfrequency to an antenna provided within the vacuum vessel in oppositionto a substrate placed on a substrate electrode within the vacuum vesselwhile interior of the vacuum vessel is controlled to a specifiedpressure by supplying gas into the vacuum vessel and simultaneouslyexhausting the interior of the vacuum vessel, and thus processing a highmelting metal (high melting temperature metal) film formed on thesubstrate,

[0012] the method comprising:

[0013] additionally supplying a high-frequency power of a 100 kHz to 20MHz frequency different from the above frequency to the antenna toprocess the substrate.

[0014] According to a second aspect of the present invention, there isprovided the plasma processing method according to the first aspect,wherein the high melting metal film is a film containing at least oneelement selected from among iridium, rhodium, ruthenium, platinum, gold,copper, rhenium, bismuth, strontium, barium, zirconium, lead, andniobium.

[0015] According to a third aspect of the present invention, there isprovided the plasma processing method according to the first aspect,wherein the substrate is processed with temperature of the antennacontrolled by giving a flow of a refrigerant to the antenna while heatconduction between the antenna and an antenna cover is ensured by anelectrically conductive sheet which is disposed between the antenna andthe antenna cover and whose surface parallel to the substrate is largerin surface area than that of the antenna, and further the substrate isprocessed while a self-bias voltage is generated up to an end portion ofthe cover by additionally supplying the high-frequency power of the 100kHz to 20 MHz frequency different from the above frequency to theantenna.

[0016] According to a fourth aspect of the present invention, there isprovided the plasma processing method according to the third aspect,wherein the plasma processing is an etching process of the high meltingmetal film formed on the substrate.

[0017] According to a fifth aspect of the present invention, there isprovided the plasma processing method according to the fourth aspectwherein the high melting metal film is a film containing at least oneelement selected from among iridium, rhodium, ruthenium, platinum, gold,copper, rhenium, bismuth, strontium, barium, zirconium, lead, andniobium.

[0018] According to a sixth aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0019] a vacuum vessel;

[0020] a gas supply unit for supplying gas into the vacuum vessel;

[0021] an exhausting unit for exhausting interior of the vacuum vessel;

[0022] a pressure-regulating valve for controlling the interior of thevacuum vessel to a specified pressure;

[0023] a substrate electrode for placing thereon a substrate within thevacuum vessel;

[0024] an antenna provided in opposition to the substrate electrode andcovered with an insulating antenna cover;

[0025] a first high-frequency power supply capable of supplying ahigh-frequency power of a 30 MHz to 3 GHz frequency to the antenna;

[0026] a second high-frequency power supply capable of additionallysupplying a high-frequency power of a 100 kHz to 20 MHz frequencydifferent from the above frequency to the antenna;

[0027] a refrigerant supply unit for making a refrigerant flow to theantenna; and

[0028] an electrically conductive sheet whose surface parallel to thesubstrate is larger than that of the antenna and which is providedbetween the antenna and the antenna cover.

[0029] According to a seventh aspect of the present invention, there isprovided the plasma processing apparatus according to the sixth aspect,wherein the antenna cover is made of quartz glass.

[0030] According to an eighth aspect of the present invention, there isprovided the plasma processing apparatus according to the sixth aspect,wherein the antenna cover is made of insulative silicon.

[0031] According to a ninth aspect of the present invention, there isprovided the plasma processing apparatus according to the sixth aspect,wherein the antenna cover is 1 mm to 10 mm thick.

[0032] According to a 10th aspect of the present invention, there isprovided the plasma processing apparatus according to the sixth aspect,wherein the electrically conductive sheet is made of a material having aresistivity of not more than 10 Ω·m.

[0033] According to an 11th aspect of the present invention, there isprovided the plasma processing apparatus according to the sixth aspect,wherein the electrically conductive sheet is 0.03 mm to 3 mm thick.

[0034] According to a 12th aspect of the present invention, there isprovided a plasma processing method for generating inductive-couplingtype plasma in a vacuum vessel by placing a substrate on a substrateelectrode within the vacuum vessel, supplying a first high-frequencypower of a 1 MHz to 60 MHz frequency to a feeding point which is one endof a coil provided in opposition to the substrate electrode whileinterior of the vacuum vessel is controlled to a specified pressure bysupplying gas into the vacuum vessel and simultaneously exhausting theinterior of the vacuum vessel, and thus processing the substrate or afilm formed on the substrate,

[0035] the method comprising:

[0036] while supplying a second high-frequency power of a frequencylower than that of the first high-frequency power to the coil with theother end of the coil grounded via a capacitor, processing thesubstrate.

[0037] According to a 13th aspect of the present invention, there isprovided a plasma processing method for generating inductive-couplingtype plasma in a vacuum vessel by placing a substrate on a substrateelectrode within the vacuum vessel, supplying a first high-frequencypower of a 1 MHz to 60 MHz frequency to a feeding point which is one endof a coil provided in opposition to the substrate electrode whileinterior of the vacuum vessel is controlled to a specified pressure bysupplying gas into the vacuum vessel and simultaneously exhausting theinterior of the vacuum vessel, and thus processing the substrate or afilm formed on the substrate,

[0038] the method comprising:

[0039] while supplying a second high-frequency power of a frequencylower than that of the first high-frequency power to an electrodeprovided at a vacancy of the coil, processing the substrate.

[0040] According to a 14th aspect of the present invention, there isprovided the plasma processing method according to the 12th aspect,wherein the plasma processing is an etching process of a high meltingmetal film formed on the substrate.

[0041] According to a 15th aspect of the present invention, there isprovided the plasma processing method according to the 14th aspect,wherein the high melting metal film is a film containing at least oneelement selected from among iridium, rhodium, ruthenium, platinum, gold,copper, rhenium, bismuth, strontium, barium, zirconium, lead, andniobium.

[0042] According to a 16th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0043] a vacuum vessel;

[0044] a gas supply unit for supplying gas into the vacuum vessel;

[0045] an exhausting unit for exhausting interior of the vacuum vessel;

[0046] a pressure-regulating valve for controlling the interior of thevacuum vessel to a specified pressure;

[0047] a substrate electrode for placing thereon a substrate within thevacuum vessel;

[0048] a coil provided in opposition to the substrate electrode andhaving one end grounded via a capacitor;

[0049] a first high-frequency power supply for supplying a firsthigh-frequency power of a 1 MHz to 60 MHz frequency to a feeding pointwhich is the other end of the coil; and

[0050] a second high-frequency power supply for supplying a secondhigh-frequency power of a frequency lower than that of the firsthigh-frequency power to the coil.

[0051] According to a 17th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0052] a vacuum vessel;

[0053] a gas supply unit for supplying gas into the vacuum vessel;

[0054] an exhausting unit for exhausting interior of the vacuum vessel;

[0055] a pressure-regulating valve for controlling the interior of thevacuum vessel to a specified pressure;

[0056] a substrate electrode for placing thereon a substrate within thevacuum vessel;

[0057] a coil provided in opposition to the substrate electrode;

[0058] a first high-frequency power supply for supplying a firsthigh-frequency power of a 1 MHz to 60 MHz frequency to a feeding pointwhich is one end of the coil; and

[0059] a second high-frequency power supply for supplying a secondhigh-frequency power of a frequency lower than that of the firsthigh-frequency power to an electrode provided at a vacancy of the coil.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] These and other aspects and features of the present inventionwill become clear from the following description taken in conjunctionwith the preferred embodiments thereof with reference to theaccompanying drawings, in which:

[0061]FIG. 1 is a sectional view showing constitution of a plasmaprocessing apparatus used in a first embodiment of the presentinvention;

[0062]FIG. 2 is a sectional view showing constitution of a plasmaprocessing apparatus used in a second embodiment of the presentinvention;

[0063]FIG. 3 is a sectional view showing constitution of a plasmaprocessing apparatus used in a prior-art example;

[0064]FIG. 4 is a sectional view showing constitution of a plasmaprocessing apparatus used in a third embodiment of the presentinvention;

[0065]FIG. 5 is a perspective view showing constitution of a plasmaprocessing apparatus used in a fourth embodiment of the presentinvention, as it is seen through;

[0066]FIG. 6 is a sectional view showing constitution of a plasmaprocessing apparatus used in a fifth embodiment of the presentinvention;

[0067]FIG. 7 is a perspective view showing constitution of a plasmaprocessing apparatus used in a sixth embodiment of the presentinvention, as it is seen through;

[0068]FIG. 8 is a perspective view showing constitution of a plasmaprocessing apparatus used in a seventh embodiment of the presentinvention, as it is seen through;

[0069]FIG. 9 is a sectional view showing constitution of a plasmaprocessing apparatus used in an eighth embodiment of the presentinvention; and

[0070]FIG. 10 is a sectional view showing constitution of a plasmaprocessing apparatus used in a prior-art example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] Before the description of the present invention proceeds, it isto be noted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

[0072] Hereinbelow, embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

[0073] A plasma processing method and apparatus according to a firstembodiment of the present invention is described below with reference toFIG. 1.

[0074]FIG. 1 is a sectional view of the plasma processing apparatus witha patch antenna type plasma source mounted thereon, which is used in thefirst embodiment of the present invention. Referring to FIG. 1, whileinterior of a vacuum vessel 1 is maintained to a specified pressure byintroducing a specified gas from a gas supply unit 2 into the vacuumvessel 1 serving as one example of a vacuum chamber and simultaneouslyperforming exhaustion by a turbo-molecular pump 3 as an exhausting unit,a high-frequency power of a 100 MHz frequency is supplied by an antennause high-frequency power supply 4 to an antenna 5. As a result of this,plasma is generated in the vacuum vessel 1, allowing plasma processingto be carried out on a substrate 7 placed on a substrate electrode 6.

[0075] There is also provided a substrate-electrode use high-frequencypower supply 8 for supplying high-frequency power of 400 kHz to thesubstrate electrode 6, making it possible to control ion energy thatreaches the substrate 7. The high-frequency power supplied to theantenna 5 is fed to a proximity of the center of the antenna 5 by a feedbar 10 via an antenna-use matching circuit 9. A dielectric plate 11composed of a dielectric material is sandwiched between the antenna 5and the vacuum vessel 1, and the feed bar 10 extends through a throughhole provided in the dielectric plate 11 to be brought into contact withthe antenna 5. Further, a slit 14 is provided so as to comprise agroove-shaped space between the dielectric plate 11 and a dielectricring 12 provided at a peripheral portion of the dielectric plate 11, anda ring-shaped and groove-shaped space between the antenna 5 and aconductor ring 13 provided at a peripheral portion of the antenna 5. Aninner side face of the slit 14 and the antenna 5 are covered with a 5 mmthick antenna cover 15 made of quartz glass. An electrically conductivesheet 16 whose surface parallel to the substrate 7 is larger than theantenna 5 is provided between the antenna 5 and the antenna cover 15.The conductive sheet 16 is 1 mm thick. Also, a refrigerant feedapparatus 17 for making a refrigerant flow to the antenna 5 is provided,and a refrigerant flow passage 18 is formed inside the antenna 5, whilean inlet/outlet passage for the refrigerant is provided within the feedbar 10.

[0076] A high-frequency power of a 500 kHz frequency is supplied to theantenna 5 from a self-bias generation use high-frequency power supply 19via a self-bias use matching circuit 20. A 100 MHz trap (trap circuit)21 is provided to prevent the high-frequency power of a 100 MHzfrequency for use of plasma generation from mixing into the self-biasuse matching circuit 20, and further, a high-pass filter 22 is providedto prevent the 500 kHz high-frequency power from mixing into theantenna-use matching circuit 9 for use of plasma generation.

[0077] The turbo-molecular pump 3 and an exhaust port 23 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 24for controlling the vacuum vessel 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum vessel 1 with four pillars 25.

[0078] With the plasma processing apparatus of the above-describedconstitution, as one example, the substrate 7 coated with a 200 nm thickiridium film was etched to a quantity of 100 pieces under the conditionsthat while the internal pressure of the vacuum vessel 1 was maintainedto 0.5 Pa by supplying 145 sccm of argon gas and 15 sccm of chlorine gasinto the vacuum vessel 1, 1500 W of a 100 MHz high-frequency power forplasma generation and 500 W of a 500 kHz high-frequency power forself-bias generation were supplied to the antenna 5, and simultaneously400 W of a 400 kHz high-frequency power was supplied to the substrateelectrode 6. As a result of this, only 50 or less dust particles having0.23 μm or larger particle diameters were generated on the substrate 7,which led to a dramatic improvement over the prior art in terms of thequantity of substrates that can be continuously processed withoutperforming wet maintenance of the vacuum vessel 1.

[0079] This can be attributed to the fact that generating a self-biasvoltage in the antenna cover 15 made it possible to efficiently preventany deposition of a conductive deposited film on the antenna cover 15.In fact, examining the surface state of the antenna cover 15 after a100-piece etching process of the substrate 7 coated with an iridium filmshowed no formation of any conductive deposited film. Also, since thesize of the surface of the antenna 5 parallel to the substrate 7 isquite smaller than the size of the surface of the antenna cover 15parallel to the substrate 7, it would be considered difficult togenerate a self-bias voltage up to end portions of the antenna cover 15.However, in the first embodiment, by virtue of the provision of theconductive sheet 16 whose surface parallel to the substrate 7 is largerthan that of the antenna 5, the self-bias voltage was able to begenerated up to the end portions of the antenna cover 15.

[0080] Further, when 5-min. plasma processing and 1-min. vacuum holdingwere repeated 100 times with the refrigerant temperature held at 25° C.,the temperature of the antenna cover 15 was maintained at 100° C. orless. The reason of this can be considered that a thin conductive sheet16 was interleaved between the antenna cover 15 and the antenna 5 andthat the antenna 5 was cooled by a refrigerant. Whereas a carbon sheet(NICAFIIM made by Nippon Carbon Co., Ltd.) was used as the conductivesheet 16 in this experiment, the conductive sheet 16 is soft, makingclose contact with the antenna 5 and the antenna cover 15, and thin,having a great effect in accelerating heat exchange between the antennacover 15 and the antenna 5. As a result of carrying out plasmaprocessing while the temperature of the antenna cover 15 was controlledas described above, there was no occurrence of cracks of the antennacover 15.

[0081] The above-described first embodiment of the present invention hasexemplified only a part of many variations on configuration of thevacuum vessel, structure and arrangement of the plasma source, and thelike out of the application range of the present invention. Needless tosay, other many variations are conceivable in applying the presentinvention, other than the example given above.

[0082] Whereas the present invention has been exemplified by a casewhere the plasma processing is an etching of a substrate coated with aniridium film, the present invention is also applicable to other variousetching processes or plasma CVD processes. However, the presentinvention is effective particularly for etching of high melting metal(high melting temperature metal) films, because the etching process ofsuch films is accompanied with a higher likelihood that a conductivedeposited film may be deposited on the antenna cover. The high meltingmetal film is not limited to iridium, and the present invention isparticularly effective for the etching process of a film containing atleast one element selected from among rhodium, ruthenium, platinum,gold, copper, rhenium, bismuth, strontium, barium, zirconium, lead, andniobium.

[0083] Whereas the present invention has been exemplified by a casewhere the antenna cover is given by 5 mm thick quartz glass, the antennacover might also be given by other ceramic based materials or insulativesilicon. However, ceramic based materials, which contain impurities inlarger part, could make a cause of dust or contamination, hence ratherbeing not preferable. Meanwhile, using insulative silicon produces aneffect of improving the etching selection ratio in the etching processof insulating films such as silicon oxide or the like. Further, sincetoo thin an antenna cover would cause an insufficiency of mechanicalstrength, and since too thick an antenna cover would cause the coolingefficiency to lower due to a heat storage effect, the antenna cover is,preferably, about 1 mm to 10 mm thick.

[0084] Whereas the present invention has been exemplified by a casewhere the conductive sheet is a uniform-in-thickness, 1 mm thick carbonsheet, thickness and material of the conductive sheet are not limited tothese. It is preferable, however, that the thermal conductivity of theconductive sheet is not less than 0.1 W/m·K. The conductive sheet isdesirably soft and highly close-contactable in order to fulfill the heatexchange between the antenna and the antenna cover, but too thin aconductive sheet would make it hard to absorb the insufficiency ofplanarity of the antenna or the antenna cover and too thick a conductivesheet would cause the conductive sheet itself to increase in heatcapacity, thus the conductive sheet being preferably about 0.03 mm to 3mm thick. Further, a larger resistivity of the conductive sheet wouldlead to occurrence of loss due to an effect of the high-frequency powersupplied to the antenna, which in some cases would lead to occurrence ofheat generation or melting of the sheet, thus the resistivity beingdesirably not more than 10 Ω·m.

[0085] Also, the above embodiment has been described on a case where thefrequency of the high-frequency power for plasma generation applied tothe antenna is 100 MHz. However, for the patch antenna used in thepresent invention, frequencies of 30 MHz to 3 GHz can be used.

[0086] Also, the above embodiment has been described on a case where thefrequency of the self-bias use high-frequency power applied to theantenna is 500 kHz. However, high-frequency power of other frequencies,e.g. 100 kHz to 20 MHz, can be used. Nevertheless, in order toeffectively generate the self-bias voltage to the antenna cover, it ispreferable to use a high-frequency power of about 100 kHz to 1 MHz.

[0087] Also, the above embodiment has been described on a case where thefrequency of the high-frequency power supplied to the substrateelectrode is 400 kHz. However, it is needless to say that high-frequencypower of other frequencies, e.g. 100 kHz to 100 MHz, can be used for thecontrol of ion energy that reaches the substrate. Otherwise, without thesupply of high-frequency power to the substrate electrode, it is alsopossible to carry out plasma processing with weak ion energy by makinguse of a slight difference between plasma potential and substratepotential. Furthermore, using a frequency different from the frequencyof the self-bias use high-frequency power supplied to the antenna has anadvantage that interference of high frequencies can be avoided.

[0088] A case where a plasma processing method and apparatus accordingto a second embodiment of the present invention having such aconstitution as shown in FIG. 2 that uses no antenna cover is used isalso within the application range of the present invention. Referring toFIG. 2, while interior of a vacuum vessel 1 is maintained to a specifiedpressure by introducing a specified gas from a gas supply unit 2 intothe vacuum vessel 1 serving as one example of a vacuum chamber andsimultaneously performing exhaustion by a turbo-molecular pump 3 as anexhausting unit, a high-frequency power of a 100 MHz frequency issupplied by an antenna use high-frequency power supply 4 to an antenna5. As a result of this, plasma is generated in the vacuum vessel 1,allowing plasma processing to be carried out on a substrate 7 placed ona substrate electrode 6. There is also provided a substrate-electrodeuse high-frequency power supply 8 for supplying high-frequency power of400 kHz to the substrate electrode 6, making it possible to control ionenergy that reaches the substrate 7. The high-frequency power suppliedto the antenna 5 is fed to a proximity of the center of the antenna 5 bya feed bar 10 via an antenna-use matching circuit 9. A dielectric plate11 constructed by a dielectric material is sandwiched between theantenna 5 and the vacuum vessel 1, and the feed bar 10 extends through athrough hole provided in the dielectric plate 11.

[0089] A high-frequency power of a 500 kHz frequency is supplied to theantenna 5 from a self-bias generation use high-frequency power supply 19via a self-bias use matching circuit 20. A 100 MHz trap (trap circuit)21 is provided to prevent the high-frequency power of a 100 MHzfrequency for use of plasma generation from mixing into the self-biasuse matching circuit 20, and further, a high-pass filter 22 is providedto prevent the 500 kHz high-frequency power from mixing into theantenna-use matching circuit 9 for use of plasma generation.

[0090] The turbo-molecular pump 3 and an exhaust port 23 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 24for controlling the vacuum vessel 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum vessel 1 with four pillars 25.

[0091] Also with the plasma processing apparatus shown in FIG. 2, thedeposition of conductive deposited film on the antenna can effectivelybe prevented in the etching process of high melting metal.

[0092] As apparent from the above description, according to the plasmaprocessing method in the first aspect of the present invention, there isprovided the plasma processing method in which the substrate is placedon the substrate electrode within the vacuum vessel, and the plasma isgenerated by supplying the high-frequency power of a 30 MHz to 3 GHzfrequency to the antenna provided in opposition to the substrateelectrode while interior of the vacuum vessel is controlled to thespecified pressure by supplying gas into the vacuum vessel andsimultaneously exhausting the interior of the vacuum vessel and thusetching is performed on the high melting metal film formed on thesubstrate, wherein the substrate is processed wall which ahigh-frequency power of a 100 kHz to 20 MHz frequency different from theabove frequency is additionally supplied to the antenna. Therefore, theplasma processing method which is less liable to occurrence of dust canbe provided.

[0093] Also, according to the plasma processing method in the thirdaspect of the present invention, there is provided the plasma processingmethod in which the substrate is placed on the substrate electrodewithin the vacuum vessel, and the plasma is generated by supplying thehigh-frequency power of a 30 MHz to 3 GHz frequency to the antennaprovided in opposition to the substrate electrode and covered with theinsulating antenna cover while interior of the vacuum vessel iscontrolled to the specified pressure by supplying gas into the vacuumvessel and simultaneously exhausting the interior of the vacuum vesseland thus the substrate is processed, wherein the substrate is processedwith temperature of the antenna controlled by giving a flow of therefrigerant to the antenna while ensuring heat conduction between theantenna and the antenna cover by the electrically conductive sheet whichis disposed between the antenna and the antenna cover and whose surfaceparallel to the substrate is larger in size than the antenna, andfurther the substrate is processed while the self-bias voltage isgenerated up to an end portion of the cover by additionally supplyingthe high-frequency power of the 100 kHz to 20 MHz frequency differentfrom the above frequency to the antenna. Therefore, the plasmaprocessing method which is less liable to occurrence of dust and cracksof the antenna cover can be provided.

[0094] Also, according to the plasma processing apparatus in the sixthaspect of the present invention, there is provided the plasma processingapparatus comprising: the vacuum vessel; the gas supply unit forsupplying gas into the vacuum vessel; the exhausting unit for exhaustinginterior of the vacuum vessel; the pressure-regulating valve forcontrolling the interior of the vacuum vessel to the specified pressure;the substrate electrode for placing thereon the substrate within thevacuum vessel; the antenna provided in opposition to the substrateelectrode and covered with the insulating antenna cover; thehigh-frequency power supply capable of supplying the high-frequencypower of the 30 MHz to 3 GHz frequency to the antenna; thehigh-frequency power supply capable of additionally supplying thehigh-frequency power of the 100 kHz to 20 MHz frequency different fromthe above frequency to the antenna; and the refrigerant supply unit formaking the refrigerant flow to the antenna, wherein the electricallyconductive sheet whose surface parallel to the substrate is larger insize than the antenna and which is provided between the antenna and theantenna cover. Therefore, the plasma processing apparatus which is lessliable to occurrence of dust and cracks of the antenna cover can beprovided.

[0095] Next, an object of plasma processing methods and apparatusesaccording to third to eighth embodiments of the present invention is toprovide a plasma processing method and apparatus which is less liable tooccurrence of dust and capable of obtaining a stable etching rate.

[0096] First of all, plasma processing using an inductive-coupling typeplasma source is described below as an example of prior-art plasmaprocessing methods with reference to FIG. 10. Referring to FIG. 10,while interior of a vacuum vessel 201 is maintained to a specifiedpressure with a pressure-regulating valve 204 by introducing a specifiedgas from a gas supply unit 202 into the vacuum vessel 201 andsimultaneously performing exhaustion by a turbo-molecular pump 203 as anexhausting unit, a high-frequency power of 13.56 MHz is supplied by acoil use high-frequency power supply 205 to a coil 208 provided along adielectric plate 207 opposed to a substrate electrode 206. Then,inductive-coupling type plasma is generated in the vacuum vessel 201,allowing plasma processing to be carried out on a substrate 209 placedon the substrate electrode 206. There is also provided asubstrate-electrode use high-frequency power supply 210 for supplying ahigh-frequency power to the substrate electrode 206, making it possibleto control ion energy that reaches the substrate 209. Theturbo-molecular pump 203 and an exhaust port 211 are disposed just underthe substrate electrode 206, and the pressure-regulating valve 204 is anup-and-down valve disposed just under the substrate electrode 206 andjust over the turbo-molecular pump 203. The substrate electrode 206 isfixed to the vacuum vessel 201 with four pillars 212.

[0097] In the plasma processing described in the prior-art example,however, there has been an issue that a deposited film caused byreaction is more likely to be deposited onto the inner wall surface ofthe dielectric plate 207 during continued process. In particular,etching a high melting metal film formed on the substrate 209 wouldinvolve deposition of an electrically conductive deposited film on thedielectric plate 207, in which case poor close-contactability of theconductive deposited film or occurrence of abnormal discharge at thesurface of the dielectric plate 207 would make it more likely to occurthat the conductive deposited film would be peeled off, falling onto thesubstrate 209 as dust in some cases. According to a result of ourexperiments, when the substrate 209 coated with a 200 nm thick iridiumfilm was etched to a quantity of 50 pieces, 1000 or more dust particleshaving 0.23 μm or larger particle diameters were generated on thesubstrate 209.

[0098] Further, in the plasma processing described in the prior-artexample, there is another issue that continued etching of the substrate209 with an iridium film would cause a conductive deposited film to bedeposited onto the dielectric plate 207 so that the conductive depositedfilm makes a shielding against the high-frequency electromagnetic fieldgenerated from the coil 208, causing an induction field formed withinthe vacuum vessel 201 to be weakened, with a result of lowered plasmadensity and, therefore, lowered etching rate. According to a result ofour experiments, as a result of etching the substrate 209 coated with a200 nm thick iridium film to a quantity of 50 pieces, whereas theinitial etching rate was 102 nm/min., the etching rate after a 50-pieceetching process lowered to 81 nm/min.

[0099] Accordingly, the plasma processing methods and apparatusesaccording to the third to eighth embodiments of the present inventionare intended to provide plasma processing methods and apparatuses whichare less liable to occurrence of dust and capable of obtaining a stableetching rate.

[0100] First, the third embodiment of the present invention is describedbelow with reference to FIG. 4.

[0101]FIG. 4 is a sectional view of a plasma processing apparatus withan inductive-coupling type plasma source mounted thereon, which is usedin the third embodiment of the present invention. Referring to FIG. 4,while interior of a vacuum vessel 101 is maintained to a specifiedpressure with a pressure-regulating valve 104 by introducing a specifiedgas from a gas supply unit 102 into the vacuum vessel 101 serving as oneexample of a vacuum chamber and simultaneously performing exhaustion bya turbo-molecular pump 103 as an exhausting unit, a first high-frequencypower of 13.56 MHz is supplied by a coil-use first high-frequency powersupply 105 to a coil 108 provided along a dielectric plate 107 opposedto a substrate electrode 106. Then, inductive-coupling type plasma isgenerated in the vacuum vessel 101, allowing plasma processing to becarried out on a substrate 109 placed on the substrate electrode 106 oron a film formed on the substrate 109. There is also provided asubstrate-electrode use high-frequency power supply 110 for supplying ahigh-frequency power to the substrate electrode 106, making it possibleto control ion energy that reaches the substrate 109. Theturbo-molecular pump 103 and an exhaust port 111 are disposed just underthe substrate electrode 106, and the pressure-regulating valve 104 is anup-and-down valve disposed just under the substrate electrode 106 andjust over the turbo-molecular pump 103. The substrate electrode 106 isfixed to the vacuum vessel 101 with four pillars 112.

[0102] A feeding point 113, which is one end of the coil 108, is locatedat the center of a spiral formed by the coil 108. The other end 114 ofthe coil 108 is grounded via a capacitor 115. The capacitor 115 has acapacity of 1000 pF. Further, a coil-use second high-frequency powersupply 116 for supplying a second high-frequency power of a 500 kHzfrequency, lower than 13.56 MHz of the first high-frequency power, tothe coil 108 is provided and connected to the feeding point 113 of thecoil 108.

[0103] Also, a band-pass filter 117 is provided as a circuit forpreventing any influences of modulation by the second high-frequencypower from being exerted on the detection circuit system for reflectedwaves of the first high-frequency power. This is intended to eliminateany effects of fluctuations of the sheath thickness of the surface ofthe dielectric plate 107 by 500 kHz due to the supply of the secondhigh-frequency power and to thereby take out and detect only the 13.56MHz component out of the reflected waves of the first high-frequencypower. In such an arrangement, carrying out processes while monitoringthe reflected waves of the first high-frequency power by areflected-wave meter 118 makes it possible to detect any trouble withthe matching state or the coil-use first high-frequency power supply inreal time. In addition, assuming that the frequency of the firsthigh-frequency power is f₁ and the frequency of the secondhigh-frequency power is f₂, the band-pass filter 117 preferably has suchfrequency characteristics that its center frequency is set to aproximity of f₁ and that its damping factor is 10 dB or more at f₁±f₂.

[0104] With the plasma processing apparatus of the above-describedconstitution, as one example, the substrate 109 coated with a 200 nmthick iridium film was etched to a quantity of 50 pieces under theconditions that while the internal pressure of the vacuum vessel 101 wasmaintained to 0.5 Pa by supplying 145 sccm of argon gas and 15 sccm ofchlorine gas into the vacuum vessel 101, 1500 W of the firsthigh-frequency power and 500 W of the second high-frequency power weresupplied to the coil 108, and simultaneously 400 W of a 400 kHzhigh-frequency power was supplied to the substrate electrode 106. As aresult of this, only 50 or less dust particles having 0.23 μm or largerparticle diameters were generated on the substrate 109, which led to adramatic improvement over the prior art in terms of the quantity ofsubstrates that can be continuously processed without performing wetmaintenance of the vacuum vessel 101. Also, whereas the initial etchingrate was 102 nm/min., the etching rate after a 50-piece etching processlowered to 101 nm/min., thus freeing from occurrence of such lowering ofetching rate as would be seen in the prior art.

[0105] This can be attributed to the fact that an ion bombardment wasgenerated on the surface of the dielectric plate 107 as a result ofcapacitively coupling the coil 108 and plasma together, making itpossible to effectively prevent the deposition of any conductivedeposited film on the dielectric plate 107. In fact, examining thesurface state of the dielectric plate 107 after a 50-piece etchingprocess of the substrate 109 coated with an iridium film showed noformation of any conductive deposited film.

[0106] The above-described embodiment of the present invention hasexemplified only a part of many variations on configuration of thevacuum vessel, structure and arrangement of the plasma source, and thelike out of the application range of the present invention. Needless tosay, other many variations are conceivable in applying the presentinvention, other than the example given above.

[0107] For example, as shown in the fourth embodiment of the presentinvention in FIG. 5, the coil 108A may also be of a multiple spiraltype. In this case, the coil 108A is low in inductance, having anadvantage that a good matching state can more easily be obtained forhigh frequencies or large-scale coils. Further, as shown in the fifthembodiment of the present invention in FIG. 6, the coil 108B may be of acylindrical type. In this case, a dielectric cylinder 119 is used inplace of the dielectric plate.

[0108] The above-described third embodiment of the present invention hasbeen exemplified by a case where the frequency of the firsthigh-frequency power is 13.56 MHz and the frequency of the secondhigh-frequency power is 500 kHz. However, it is considered preferablethat the frequency of the second high-frequency power is not more than{fraction (1/10)} of the frequency of the first high-frequency power. Inthe third embodiment of the present invention, since the capacity of thecapacitor 115 is 1000 pF, the impedance of the capacitor for the firsthigh-frequency power is

1/(2π×13.56×10⁶×1000×10⁻¹²)=12 Ω.

[0109] For the second high-frequency power, on the other hand, theimpedance is

1/(2π×500×10³×1000×10⁻¹²)=320 Ω.

[0110] Since the inductance of the coil 108 was 0.8 μH, the impedance ofthe coil 108 for the first high-frequency power is

2π×13.56×10⁶×0.8×10⁻⁶=68 Ω.

[0111] For the second high-frequency power, on the other hand, theimpedance is

2π×500×10³×0.8×10⁻⁶=2.5 Ω.

[0112] Therefore, the ratio of a voltage applied to the coil 108 to avoltage applied to the capacitor 115 for the first high-frequency poweris

68÷12=5.7,

[0113] and for the second high-frequency power, it is

2.5÷320=0.0078.

[0114] Therefore, it can be understood that a series circuit of the coil108 and the capacitor 115 is nearly inductive (coil component) as viewedfrom the first high-frequency power, and nearly capacitive (capacitorcomponent) as viewed from the second high-frequency power. That is,while inductive-coupling type plasma is generated with the firsthigh-frequency power, the coil 108 and the plasma can be capacitivelycoupled together with the second high-frequency power so that an ionbombardment due to the self-bias voltage can be given to the surface ofthe dielectric plate 107 or the dielectric cylinder 119. It can beconsidered that such a relationship holds when the frequency of thesecond high-frequency power is not more than generally {fraction (1/10)}of the frequency of the first high-frequency power. If the frequency ofthe second high-frequency power is larger than {fraction (1/10)} of thefrequency of the first high-frequency power, the difference in the ratioof the voltage applied to the coil 108 to the voltage applied to thecapacitor 115 between the first high-frequency power and the secondhigh-frequency power would be too small, making it hard to expect theintended effect.

[0115] Even in the prior-art example, since the high-frequency voltageis relatively large in vicinities of the center of the coil 108, therewould occur some degree of ion bombardment due to the self-bias voltagein vicinities of the center of the dielectric plate 107. However, sincethe high-frequency voltage is low in vicinities of the outer peripheryof the coil 108, there would occur almost no ion bombardment due to theself-bias voltage in vicinities of the outer periphery of the dielectricplate 107. Further, the present invention has an advantage that plasmadensity is controlled by the magnitude of the first high-frequency powerand, independently of this, the ion bombardment can be controlled by themagnitude of the second high-frequency power.

[0116] Also, if the impedance of the coil against the firsthigh-frequency power is not less than a double of the impedance of thecapacitor and the impedance of the coil against the secondhigh-frequency power is not more than {fraction (1/5)} of the impedanceof the capacitor, then enough difference in the ratio of the voltageapplied to the coil 108 to the voltage applied to the capacitor 115between the first high-frequency power and the second high-frequencypower can be obtained, which is considered effective. When theseconditions are not satisfied, there would result too small a differencein the ratio of the voltage applied to the coil 108 to the voltageapplied to the capacitor 115 between the first high-frequency power andthe second high-frequency power, making it hard to expect the intendedeffect. In addition, when multiple coils are used as in the fourthembodiment of the present invention, it is appropriate that theimpedance be considered for each one pair of coil and capacitor.

[0117] Also, if the impedance of the capacitor against the firsthigh-frequency power is not more than 25 Ω and the impedance of thecapacitor against the second high-frequency power is not less than 250Ω, then enough difference in the ratio of the voltage applied to thecoil 108 to the voltage applied to the capacitor 115 between the firsthigh-frequency power and the second high-frequency power can beobtained, which is considered effective. When these conditions are notsatisfied, there would result too small a difference in the ratio of thevoltage applied to the coil 108 to the voltage applied to the capacitor115 between the first high-frequency power and the second high-frequencypower, making it hard to expect the intended effect. In addition, whenmultiple coils are used as in the fourth embodiment of the presentinvention, it is appropriate that the impedance be considered for eachone pair of coil and capacitor.

[0118] Also, if the impedance of the coil against the firsthigh-frequency power is not less than 50 Ω and the impedance of the coilagainst the second high-frequency power is not more than 5 Ω, thenenough difference in the ratio of the voltage applied to the coil 108 tothe voltage applied to the capacitor 115 between the firsthigh-frequency power and the second high-frequency power can beobtained, which is considered effective. When these conditions are notsatisfied, there would result too small a difference in the ratio of thevoltage applied to the coil 108 to the voltage applied to the capacitor115 between the first high-frequency power and the second high-frequencypower, making it hard to expect the intended effect. In addition, whenmultiple coils are used as in the fourth embodiment of the presentinvention, it is appropriate that the impedance be considered for eachone pair of coil and capacitor.

[0119] Next, a sixth embodiment of the present invention is describedwith reference to FIG. 7.

[0120]FIG. 7 is a perspective view of a plasma processing apparatushaving an inductive-coupling type plasma source mounted thereon, whichis used in the sixth embodiment of the present invention. Referring toFIG. 7, while interior of a vacuum vessel 101 is maintained to aspecified pressure with a pressure-regulating valve 104 by introducing aspecified gas from a gas supply unit 102 into the vacuum vessel 101 andsimultaneously performing exhaustion by a turbo-molecular pump 103 as anexhausting unit, a first high-frequency power of 13.56 MHz is suppliedby a coil-use first high-frequency power supply 105 to a coil 108provided along a dielectric plate 107 opposed to a substrate electrode106. Then, inductive-coupling type plasma is generated in the vacuumvessel 101, allowing plasma processing to be carried out with asubstrate 109 placed on the substrate electrode 106 or with a filmformed on the substrate 109. There is also provided asubstrate-electrode use high-frequency power supply 110 for supplyinghigh-frequency power to the substrate electrode 106, making it possibleto control ion energy that reaches the substrate 109. Theturbo-molecular pump 103 and an exhaust port 111 are disposed just underthe substrate electrode 106, and the pressure-regulating valve 104 is anup-and-down valve disposed just under the substrate electrode 106 andjust over the turbo-molecular pump 103. The substrate electrode 106 isfixed to the vacuum vessel 101 with four pillars 112.

[0121] A feeding point 113, which is one end of the coil 108, is locatedat the center of a spiral formed by the coil 108. Further, there isprovided an electrode-use second high-frequency power supply 116 forsupplying a second high-frequency power of a frequency, which is lowerthan the frequency of the first high-frequency power, to an electrode120 provided at a vacancy of the coil. Although the secondhigh-frequency power is applied to the center of the spiral formed bythe electrode 120 in this embodiment, yet it may also be applied to anouter peripheral end of the spiral and moreover the feeding points donot necessarily need to be end portions. Also, the electrode 120 is notgrounded.

[0122] Also, a band-pass filter 117 is provided as a circuit forpreventing any influences of modulation by the second high-frequencypower from being exerted on the detection circuit system for reflectedwaves of the first high-frequency power. This is intended to eliminateany effects of fluctuations of the sheath thickness of the surface ofthe dielectric plate 107 by 500 kHz due to the supply of the secondhigh-frequency power and to thereby take out and detect only the 13.56MHz component out of the reflected waves of the first high-frequencypower. In such an arrangement, carrying out processes while monitoringthe reflected waves of the first high-frequency power by areflected-wave meter 118 makes it possible to detect any trouble withthe matching state or the coil-use first high-frequency power supply inreal time. In addition, assuming that the frequency of the firsthigh-frequency power is f₁ and the frequency of the secondhigh-frequency power is f₂, the band-pass filter 117 preferably has suchfrequency characteristics that its center frequency is set to aproximity of f₁ and that its damping factor is 10 dB or more at f₁±f₂.

[0123] With the plasma processing apparatus of the above-describedconstitution, as one example, the substrate 109 coated with a 200 nmthick iridium film was etched to a quantity of 50 pieces under theconditions that while the internal pressure of the vacuum vessel 101 wasmaintained to 0.5 Pa by supplying 145 sccm of argon gas and 15 sccm ofchlorine gas into the vacuum vessel 101, 1500 W of the firsthigh-frequency power was supplied to the coil 108 and 500 W of thesecond high-frequency power was supplied to the electrode 120, andsimultaneously 400 W of a 400 kHz high-frequency power was supplied tothe substrate electrode 106. As a result of this, only 50 or less dustparticles having 0.23 μm or larger particle diameters were generated onthe substrate 109, which led to a dramatic improvement over the priorart in terms of the quantity of substrates that can be continuouslyprocessed without performing wet maintenance of the vacuum vessel 101.Also, whereas the initial etching rate was 98 nm/min., the etching rateafter a 50-piece etching process was 97 nm/min., thus freeing fromoccurrence of such lowering of etching rate as would be seen in theprior art.

[0124] This can be attributed to the fact that an ion bombardment wasgenerated on the surface of the dielectric plate 107 as a result ofcapacitively coupling the electrode 120 and plasma together, making itpossible to effectively prevent the deposition of any conductivedeposited film on the dielectric plate 107. In fact, examining thesurface state of the dielectric plate 107 after a 50-piece etchingprocess of the substrate 109 coated with an iridium film showed noformation of any conductive deposited film.

[0125] The above-described embodiment of the present invention hasexemplified only a part of many variations on configuration of thevacuum vessel, structure and arrangement of the plasma source, and thelike out of the application range of the present invention. Needless tosay, other many variations are conceivable in applying the presentinvention, other than the example given above.

[0126] For example, as shown in the seventh embodiment of the presentinvention in FIG. 8, the coil 108 may also be of a multiple spiral type.In this case, the coil 108 is low in inductance, having an advantagethat a good matching state can more easily be obtained for highfrequencies or large-scale coils. In this case, preferably, theelectrode 120 is also of a multiple spiral structure as a whole as shownin FIG. 8. Further, as shown in the eighth embodiment of the presentinvention in FIG. 9, the coil 108 may be of a cylindrical type. In thiscase, a dielectric cylinder 119 is used in place of the dielectricplate. Further, preferably, the electrode 120B is also of a cylindricalspiral configuration.

[0127] The above sixth embodiment of the present invention has beenexemplified by a case where the frequency of the high-frequency power is13.56 MHz and the frequency of the second high-frequency power is 500kHz. However, it is considered preferable that the frequency of thesecond high-frequency power is not more than {fraction (1/10)} of thefrequency of the first high-frequency power. With such a relationship,there is an advantage that interference between the first high-frequencypower and the second high-frequency power is less likely to occur.

[0128] Whereas the above embodiment of the present invention has beenexemplified by a case where the plasma processing is an etching of asubstrate coated with an iridium film, the present invention is alsoapplicable to other various etching processes and plasma CVD processes.This is because in general there are many cases where the deposition ofa deposited film onto the dielectric plate or the dielectric cylinderwould matter in etching process or plasma CVD process. However, thepresent invention is effective particularly for etching of high meltingmetal films, because the etching process of such films is accompanied bya higher likelihood that a conductive deposited film may be deposited onthe dielectric plate or the dielectric cylinder. The high melting metalfilm is not limited to iridium, and the present invention isparticularly effective for the etching process of films containing atleast one element selected from among rhodium, ruthenium, platinum,gold, copper, rhenium, bismuth, strontium, barium, zirconium, lead, andniobium.

[0129] Also, the above embodiments have been exemplified by a case wherethe frequency of the first high-frequency power supplied to the coil is13.56 MHz. However, in order to effectively generate theinductive-coupling type plasma, it is preferable to use frequencies of 1MHz to 60 MHz. Frequencies lower than 1 MHz would cause a drawback thatenough plasma density could not be obtained, while frequencies higherthan 60 MHz would cause occurrence of standing waves to the coil, makingit quite hard to obtain uniform plasma.

[0130] Also, the above embodiments have been exemplified by a case wherethe frequency of the high-frequency power supplied to the substrateelectrode is 400 kHz. However, it is needless to say that high-frequencypower of other frequencies, e.g. 100 kHz to 100 MHz, can be used for thecontrol of ion energy that reaches the substrate. Otherwise, without thesupply of high-frequency power to the substrate electrode, it is alsopossible to carry out plasma processing with weak ion energy by makinguse of a slight difference between plasma potential and substratepotential. Furthermore, as to the frequency of the high-frequency powersupplied to the substrate electrode, using a frequency different fromthe frequency of the second high-frequency power supplied to the coil orthe electrode has an advantage that interference of high frequencies canmore easily be avoided.

[0131] As apparent from the above description, according to the plasmaprocessing method in the 12th aspect of the present invention, there isprovided the plasma processing method in which the substrate is placedon the substrate electrode within the vacuum vessel, and theinductive-coupling type plasma is generated in the vacuum vessel bysupplying the first high-frequency power of a 1 MHz to 60 MHz frequencyto the feeding point which is one end of the coil provided in oppositionto the substrate electrode while interior of the vacuum vessel iscontrolled to the specified pressure by supplying the gas into thevacuum vessel and simultaneously exhausting the interior of the vacuumvessel and thus the substrate or the film formed on the substrate isprocessed, wherein the substrate is processed while the secondhigh-frequency power of a frequency lower than that of the firsthigh-frequency power is supplied to the coil with the other end of thecoil grounded via the capacitor. Therefore, the plasma processing methodwhich is less liable to occurrence of dust and capable of obtaining astable etching rate can be provided.

[0132] Also, according to the plasma processing method in the 13thaspect of the present invention, there is provided the plasma processingmethod in which the substrate is placed on the substrate electrodewithin the vacuum vessel, the inductive-coupling type plasma isgenerated in the vacuum vessel by supplying the first high-frequencypower of a 1 MHz to 60 MHz frequency to the feeding point which is oneend of the coil provided in opposition to the substrate electrode whileinterior of the vacuum vessel is controlled to the specified pressure bysupplying the gas into the vacuum vessel and simultaneously exhaustingthe interior of the vacuum vessel, and thus the substrate or the filmformed on the substrate is processed, wherein the substrate is processedwhile the second high-frequency power of a frequency lower than that ofthe first high-frequency power is supplied to the electrode provided atthe vacancy of the coil to process the substrate. Therefore, the plasmaprocessing method which is less liable to occurrence of dust and capableof obtaining a stable etching rate can be provided.

[0133] Also, according to the plasma processing apparatus in the 16thaspect of the present invention, there is provided the plasma processingapparatus comprising: the vacuum vessel; the gas supply unit forsupplying the gas into the vacuum vessel; the exhausting unit forexhausting the interior of the vacuum vessel; the pressure-regulatingvalve for controlling the interior of the vacuum vessel to the specifiedpressure; the substrate electrode for placing thereon the substratewithin the vacuum vessel; the coil provided in opposition to thesubstrate electrode; and the first high-frequency power supply forsupplying the first high-frequency power of the 1 MHz to 60 MHzfrequency to the feeding point which is one end of the coil, wherein theother end of the coil is grounded via the capacitor, and the plasmaprocessing apparatus further comprises the second high-frequency powersupply for supplying the second high-frequency power of a frequencylower than that of the first high-frequency power to the coil.Therefore, the plasma processing apparatus which is less liable tooccurrence of dust and capable of obtaining a stable etching rate can beprovided.

[0134] Also, according to the plasma processing apparatus in the 17thaspect of the present invention, there is provided the plasma processingapparatus comprising: the vacuum vessel; the gas supply unit forsupplying the gas into the vacuum vessel; the exhausting unit forexhausting the interior of the vacuum vessel; the pressure-regulatingvalve for controlling the interior of the vacuum vessel to the specifiedpressure; the substrate electrode for placing thereon the substratewithin the vacuum vessel; the coil provided in opposition to thesubstrate electrode; the first high-frequency power supply for supplyingthe first high-frequency power of a 1 MHz to 60 MHz frequency to thefeeding point which is one end of the coil, wherein the plasmaprocessing apparatus further comprises the second high-frequency powersupply for supplying the second high-frequency power of a frequencylower than that of the first high-frequency power to the electrodeprovided at the vacancy of the coil. Therefore, the plasma processingapparatus which is less liable to occurrence of dust and capable ofobtaining a stable etching rate can be provided.

[0135] In addition, combining any arbitrary embodiments togetherappropriately from among the foregoing various embodiments allows theirrespective effects to be produced.

[0136] Although the present invention has been fully described inconnection with the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A plasma processing method for generating plasmain a vacuum vessel, by supplying a high-frequency power of a 30 MHz to 3GHz frequency to an antenna provided within the vacuum vessel inopposition to a substrate placed on a substrate electrode within thevacuum vessel while interior of the vacuum vessel is controlled to aspecified pressure by supplying gas into the vacuum vessel andsimultaneously exhausting the interior of the vacuum vessel, and thusprocessing a high melting metal film formed on the substrate, the methodcomprising: additionally supplying a high-frequency power of a 100 kHzto 20 MHz frequency different from the above frequency to the antenna toprocess the substrate.
 2. The plasma processing method according toclaim 1, wherein the high melting metal film is a film containing atleast one element selected from among iridium, rhodium, ruthenium,platinum, gold, copper, rhenium, bismuth, strontium, barium, zirconium,lead, and niobium.
 3. The plasma processing method according to claim 1,wherein the substrate is processed with temperature of the antennacontrolled by giving a flow of a refrigerant to the antenna while heatconduction between the antenna and an antenna cover is ensured by anelectrically conductive sheet which is disposed between the antenna andthe antenna cover and whose surface parallel to the substrate is largerin surface area than that of the antenna, and further the substrate isprocessed while a self-bias voltage is generated up to an end portion ofthe cover by additionally supplying the high-frequency power of the 100kHz to 20 MHz frequency different from the above frequency to theantenna.
 4. The plasma processing method according to claim 3, whereinthe plasma processing is an etching process of the high melting metalfilm formed on the substrate.
 5. The plasma processing method accordingto claim 4, wherein the high melting metal film is a film containing atleast one element selected from among iridium, rhodium, ruthenium,platinum, gold, copper, rhenium, bismuth, strontium, barium, zirconium,lead, and niobium.
 6. A plasma processing apparatus comprising: a vacuumvessel; a gas supply unit for supplying gas into the vacuum vessel; anexhausting unit for exhausting interior of the vacuum vessel; apressure-regulating valve for controlling the interior of the vacuumvessel to a specified pressure; a substrate electrode for placingthereon a substrate within the vacuum vessel; an antenna provided inopposition to the substrate electrode and covered with an insulatingantenna cover; a first high-frequency power supply capable of supplyinga high-frequency power of a 30 MHz to 3 GHz frequency to the antenna; asecond high-frequency power supply capable of additionally supplying ahigh-frequency power of a 100 kHz to 20 MHz frequency different from theabove frequency to the antenna; a refrigerant supply unit for making arefrigerant flow to the antenna; and an electrically conductive sheetwhose surface parallel to the substrate is larger than that of theantenna and which is provided between the antenna and the antenna cover.7. The plasma processing apparatus according to claim 6, wherein theantenna cover is made of quartz glass.
 8. The plasma processingapparatus according to claim 6, wherein the antenna cover is made ofinsulative silicon.
 9. The plasma processing apparatus according toclaim 6, wherein the antenna cover is 1 mm to 10 mm thick.
 10. Theplasma processing apparatus according to claim 6, wherein theelectrically conductive sheet is made of a material having a resistivityof not more than 10 Ω·m.
 11. The plasma processing apparatus accordingto claim 6, wherein the electrically conductive sheet is 0.03 mm to 3 mmthick.
 12. A plasma processing method for generating inductive-couplingtype plasma in a vacuum vessel by placing a substrate on a substrateelectrode within the vacuum vessel, supplying a first high-frequencypower of a 1 MHz to 60 MHz frequency to a feeding point which is one endof a coil provided in opposition to the substrate electrode whileinterior of the vacuum vessel is controlled to a specified pressure bysupplying gas into the vacuum vessel and simultaneously exhausting theinterior of the vacuum vessel, and thus processing the substrate or afilm formed on the substrate, the method comprising: while supplying asecond high-frequency power of a frequency lower than that of the firsthigh-frequency power to the coil with the other end of the coil groundedvia a capacitor, processing the substrate.
 13. A plasma processingmethod for generating inductive-coupling type plasma in a vacuum vesselby placing a substrate on a substrate electrode within the vacuumvessel, supplying a first high-frequency power of a 1 MHz to 60 MHzfrequency to a feeding point which is one end of a coil provided inopposition to the substrate electrode while interior of the vacuumvessel is controlled to a specified pressure by supplying gas into thevacuum vessel and simultaneously exhausting the interior of the vacuumvessel, and thus processing the substrate or a film formed on thesubstrate, the method comprising: while supplying a secondhigh-frequency power of a frequency lower than that of the firsthigh-frequency power to an electrode provided at a vacancy of the coil,processing the substrate.
 14. The plasma processing method according toclaim 12, wherein the plasma processing is an etching process of a highmelting metal film formed on the substrate.
 15. The plasma processingmethod according to claim 14, wherein the high melting metal film is afilm containing at least one element selected from among iridium,rhodium, ruthenium, platinum, gold, copper, rhenium, bismuth, strontium,barium, zirconium, lead, and niobium.
 16. A plasma processing apparatuscomprising: a vacuum vessel; a gas supply unit for supplying gas intothe vacuum vessel; an exhausting unit for exhausting interior of thevacuum vessel; a pressure-regulating valve for controlling the interiorof the vacuum vessel to a specified pressure; a substrate electrode forplacing thereon a substrate within the vacuum vessel; a coil provided inopposition to the substrate electrode and having one end grounded via acapacitor; a first high-frequency power supply for supplying a firsthigh-frequency power of a 1 MHz to 60 MHz frequency to a feeding pointwhich is the other end of the coil; and a second high-frequency powersupply for supplying a second high-frequency power of a frequency lowerthan that of the first high-frequency power to the coil.
 17. A plasmaprocessing apparatus comprising: a vacuum vessel; a gas supply unit forsupplying gas into the vacuum vessel; an exhausting unit for exhaustinginterior of the vacuum vessel; a pressure-regulating valve forcontrolling the interior of the vacuum vessel to a specified pressure; asubstrate electrode for placing thereon a substrate within the vacuumvessel; a coil provided in opposition to the substrate electrode; afirst high-frequency power supply for supplying a first high-frequencypower of a 1 MHz to 60 MHz frequency to a feeding point which is one endof the coil; and a second high-frequency power supply for supplying asecond high-frequency power of a frequency lower than that of the firsthigh-frequency power to an electrode provided at a vacancy of the coil.